1. Field of the Invention
This invention pertains to foods that are subject to spoilage and to oxidation reactions following processing and/or packaging resulting in discoloration and undesirable changes in flavor. In particular, the present invention relates to a stabilized guacamole and a process for preparing a stabilized guacamole.
2. Description of the Prior Art
Browning, or oxidative darkening, of food products can result from both enzymatic and non-enzymatic chemical reactions in food. Enzymatic browning is the result of the action of enzymes such as polyphenol oxidase that catalyze the oxidation of mono- and di-phenols to o-quinones which then polymerize spontaneously to form dark colored, high molecular weight polymers, thus leading to the characteristic browning or formation of dark spots. Browning associated with non-enzymatic chemical reactions are also commonly due to the polymerization of phenolic compounds that are present in some foods. Both enzymatic and non-enzymatic browning constitute serious problems for the foods industry and result in millions of pounds of wasted food products each year.
Several physical methods have been developed for inhibiting oxidation and the resultant browning. One of the most common and well known methods is by heat inactivation of the enzymes through pasteurization or similar processes. Another method is shown in U.S. Pat. No. 3,958,036 issued to Latimer. Latimer describes a stabilized avocado preparation that is a dispersion or emulsion of avocado, water and vegetable gums. The stated objective of the dispersion is to prevent the water from separating from the avocado thereby, presumably minimizing contact between the avocado and oxygen. However, the disclosed dispersion is stable only for between one and three months and chemical agents are preferably added to maintain color.
An additional physical method that has been developed for inhibiting oxidation is described in U.S. Pat. No. 5,384,147 to Hilpert. This patent describes the use of an extremely high vacuum process for removing substantially all of the oxygen contained in the cells of food prior to its packaging. It is also noted that in addition to removing the oxygen from the food product that the prior art also discloses the substitution of inert gases such as nitrogen and carbon dioxide into processed food to prevent further oxidation.
Similarly, U.S. Pat. No. 4,572,836 to Bakal, which is directed to the preparation of a stabilized edible herb product, notes that dehydration is commonly used to stabilize food products for storage. It is also emphasized that the dehydration process frequently results in the loss of flavor from the food and is in fact a poor means of preventing oxidation of the stored food.
In addition to the various physical processes that may be performed to inhibit oxidation, the addition of chemical agents is also well known. The use of sulfiting agents such as sulphur dioxide and sodium bisulfite to inactivate enzymes is very well known in the industry. In fact sulfite is believed to be the most effective chemical additive used to prevent enzymatic discoloration in most produce. The mechanism of sulfites is one in which o-quinones are reduced to the mono- and/or di-phenols, thereby inhibiting the oxidation reaction. However, the use of sulfites in fresh fruits and vegetables has been banned by the U.S. Food and Drug Administration due to their adverse health effects in certain individuals and it is anticipated that their use may be completely eliminated in the future.
In addition to sulfiting agents, other chemical preservation agents have been used to inhibit oxidation in various food products. Representative examples of such chemical preservation agents include discoloration inhibitors such as ascorbic acid, citric acid, sorbic acid and malic acid, in addition to other additives such as salt, EDTA, dextrose, calcium chloride, sodium acid pyrophosphate and sodium citrate. However, none of these discoloration inhibitors have been found to be as effective as sulfites.
Recognizing the problems associated with the use of sulfites, others have combined various agents with lower concentrations of sulfites to obtain the desired inhibiting effect. U.S. Pat. No. 5,202,141, to McEvily et al. describes a method and composition for inhibiting oxidative darkening containing at least one substituted resorcinol derivative and a second additive, preferably a sulfite. U.S. Pat. No. 5,389,389 to Beck discloses the use of cysteine in conjunction with a small concentration of sulfite.
As noted, there are problems associated with both the physical and chemical methods used for inhibiting the oxidation of foods. Although the physical methods described above are largely free of adverse health effects on humans, they frequently have detrimental effects on the flavor and texture of the foods and are generally poor inhibitors of oxidation reactions. In terms of the available chemical additives, good antioxidant results can be achieved with the use of sulfites but not without the accompanying health risks. Alternatively, non-sulfite chemical agents can be used with less effective results thus requiring higher concentrations of the agents and an increased risk of adversely affecting the flavoring, texture and/or coloring of the food.
The spoilage and oxidation problems associated with many foods are particularly acute in avocados, creating an unresolved need for stabilizing avocados and their preparations from premature spoilage and oxidation. Therefore it is a feature of the present invention to provide a composition of a stabilized guacamole that it is inhibited from undergoing oxidation and the accompanying discoloration and loss of flavor, the composition comprising a mixture of avocado flesh, a naturally occurring preservative found in the pulp of tomatillo and optionally containing various flavoring agents and chemical agents for controlling the pH of the composition.
It is another feature of the present invention to provide a process for preparing a stabilized guacamole composition by mixing avocado flesh with a naturally occurring preservative found in the pulp of tomatillo and heating the mixture. The process optionally includes adding various flavoring agents and controlling the pH of the composition by adding various chemical agents.
It is still another feature of the present invention to provide a stabilized guacamole that is made from the disclosed process and that is free of sulfites.
It is yet another feature of the present invention to provide a process for preparing a stabilized guacamole composition that does not require extensive physical processing steps such as complex vacuum processing, dehydration or emulsification.